NTSB Factual Report

The pilot reported that while maneuvering at a low altitude over a machinery yard, he observed a low rotor rpm condition. When he lifted the collective the rpm continued to bleed off, which resulted in the helicopter yawing to the left. The pilot stated that he managed to get the helicopter back under control, but then entered the low rotor rpm condition a second time. Unable to keep the helicopter flying straight, the aircraft impacted up sloping terrain with its left skid, which was followed by the main rotor blades striking the ground. The helicopter sustained substantial damage due to the impact with terrain.

The pilot reported no preimpact mechanical malfunctions or failures with the helicopter that would have precluded normal operation.

NTSB Probable Cause

The pilot's failure to maintain main rotor RPM during a low altitude operation, which resulted in a loss of aircraft control and collision with terrain.